Function prepare_private_surface 

pub fn prepare_private_surface(
    definition: &'static ApplicationDefinition,
    device: &str,
    person: &str,
    workspace: &str,
    instance: u64,
    lend: impl FnOnce(&mut HostContext),
) -> Result<AppComponent, LaunchError>

Prepare definition as one of the desktop’s own surface apps (the bar, the banners, Quick Settings, a sheet): as person on device, its record and view kept in memory under workspace, its window private, so nothing of it is written to disk or offered beyond this device. lend hands it what its host lends it.

Errors

The app refuses the context.